Solvent-induced luminescence quenching: Static and time-resolved X-ray absorption spectroscopy of a copper(I) phenanthroline complex

Research output: Contribution to journalArticlepeer-review

Authors

  • T. J. Penfold
  • S. Karlsson
  • G. Capano
  • F. A. Lima
  • J. Rittmann
  • M. Reinhard
  • M. H. Rittmann-Frank
  • O. Braem
  • R. Abela
  • I. Tavernelli
  • U. Rothlisberger
  • C. J. Milne
  • M. Chergui

Colleges, School and Institutes

External organisations

  • Laboratory of Photonics and Interfaces, Department de Chimie, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland. ahmad@mpip-mainz.mpg.de
  • École Polytechnique Fédérale de Lausanne
  • Laboratoire de Spectroscopie Ultrarapide
  • FSB-BSP
  • Laboratoire de Chimie et Biochimie Computationnelles
  • SwissFEL
  • Paul Scherrer Institut
  • Centro Nacional de Pesquisa em Energia e Materiais Laboratorio Nacional de Luz Sincrotron
  • Ecole Polytechnique Fédérale de Lausanne

Abstract

We present a static and picosecond X-ray absorption study at the Cu K-edge of bis(2,9-dimethyl-1,10-phenanthroline)copper(I) ([Cu(dmp)2] +; dmp = 2,9-dimethyl-1,10-phenanthroline) dissolved in acetonitrile and dichloromethane. The steady-state photoluminescence spectra in dichloromethane and acetonitrile are also presented and show a shift to longer wavelengths for the latter, which points to a stronger stabilization of the excited complex. The fine structure features of the static and transient X-ray spectra allow an unambiguous assignment of the electronic and geometric structure of the molecule in both its ground and excited 3MLCT states. Importantly, the transient spectra are remarkably similar for both solvents, and the spectral changes can be rationalized using the optimized ground- and excited-state structures of the complex. The proposed assignment of the lifetime shortening of the excited state in donor solvents (acetonitrile) to a metal-centered exciplex is not corroborated here. Molecular dynamics simulations confirm the lack of complexation; however, in both solvents the molecules come close to the metal but undergo rapid exchange with the bulk. The shortening of the lifetime of the title complex and nine additional related complexes can be rationalized by the decrease in the 3MLCT energy. Deviations from this trend may be explained by means of the effects of the dihedral angle between the ligand planes, the solvent, and the 3MLCT-1MLCT energy gap.

Details

Original languageEnglish
Pages (from-to)4591-4601
Number of pages11
JournalThe Journal of Physical Chemistry A
Volume117
Issue number22
Publication statusPublished - 3 Jul 2013

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